celestial globe; armillary sphere
A model of the celestial sphere, used historically for teaching astronomy. The two English terms refer to slightly different instruments: a celestial globe is a sphere showing stars and constellations, while an armillary sphere is a skeletal framework of rings representing celestial circles. In Japanese, 天球儀 can cover both.
I saw an Edo-period celestial globe at the museum.
Celestial globes were once used in astronomy education.